CN101910328B - Primers and a method of coating in which they are used - Google Patents

Abstract

To provide a primer which has excellent adhesion on a plastic base material and with which the inter- layer adhesion with the paint film which forms the base on recoating (repainting) is excellent, and a method of coating in which this primer is used. [Means of Resolution] A primer which is characterized in that it contains (A) chlorinated polyolefin resin which has a chlorine content of from 5 to 50 mass% and a weight average molecular weight of from 1,000 to 100,000, (B) blocked polyisocyanate compound, (C) polyol resin which has a hydroxyl group value of from 30 to 120 mgKOH/g and a weight average molecular weight from 5,000 to 50,000, (D) diol which has a weight average molecular weight of from 120 to 1,000 and (E) hardening catalyst, and the proportions with respect to the total mass of the resin solid fraction of the (A) component, the (B) component and the (C) component in which these components are included are from 50 to 90 mass% of the (A) component, from 45 to 5 mass% of the (B) component, from 45 to 5 mass% of the (C) component, from 0.5 to 12 mass% of the (D) component and from 0.01 to 1.5 mass% of the (E) component.

Description

Primers and coating methods using them

technical field

The present invention relates to primers which have excellent adhesion on plastic substrates, especially polyolefin substrates, and which when recoated (repainted) without sanding , said primers have excellent adhesion on topcoat films; and also relate to coating methods employing these primers.

Background technique

Polyolefin moldings are often used as, for example, automobile exterior panels and parts of home electric products, and more recently, recycled polyolefin moldings have begun to be recycled. In those cases where a two-pack type topcoat containing a polyisocyanate compound is used as a topcoat for a polyolefin molding, a primer containing a chlorinated polyolefin is used to improve the adhesion between the topcoat film and the polyolefin molding. Adhesiveness. However, there is a problem that rubber products (such as styrene/butadiene rubber, isoprene rubber, etc.) contained in recycled polyolefin moldings and recycled polyolefin moldings, In the case where only polyolefin containing a small amount or no hydroxyl group is added to the product, the adhesion to the polyolefin substrate is not sufficient.

In addition, in the case of repair coating after a primer and a topcoat have been applied to a polyolefin molding, the paint film is usually sanded to remove dirt and marks, and then the primer and topcoat are applied to the surface. The part is recoated (repainted). At this point, recoating with primer and topcoat can be done on the unabrased (non-sanded) paint film without sanding the entire surface of the paint film to be repaired. In this case, there is a problem that the interlayer adhesion between the undercoat paint film and the recoating primer is insufficient.

It is known that a paint composition having the following essential components is a two-liquid type paint composition which is excellent in high-gloss appearance, weather resistance, solvent resistance and coating workability, and which can be used without applying a primer. Paints that provide excellent adhesion when directly applied to polyolefin moldings where adhesion is difficult to obtain: (A) chlorinated polyolefin resins with a chlorine content of 10 to 50% by mass, (B) Acrylic modified chlorinated polyolefin resin, (C) an acrylic resin and/or polyester resin with a weight average molecular weight of 2,000-50,000 and a hydroxyl value of 10-90 mgKOH/g and (D) an isocyanate compound, wherein the isocyanate equivalent is equal to The ratio of hydroxyl equivalents [isocyanate equivalents]/[hydroxyl equivalents] is 0.5/1.0 to 1.2/1.0, and wherein, based on the total mass (solid parts) of (A), (B) and (C) components, the The (A) component accounts for 3 to 20% by mass, the (B) component accounts for 5 to 40% by mass, and the (C) component accounts for 40 to 92% by mass (for example, refer to cited patent 1). However, due to such a combination of the function of the primer and the function of the top coat, adhesion to polyolefin base moldings is insufficient, and these two-component type paints also have a problem of shelf life.

In addition, it is known that a resin composition for coating purposes having good adhesion on polyolefin substrates is a composition for coating purposes using the The composition can form a paint film with excellent adhesion, hot water resistance and gasoline resistance, the composition also has excellent paint storage stability, and can be used without any pretreatment, such as using a primer In the case of coating such as, direct coating on polyolefin substrate moldings: As an essential component, they contain (1) polymers having acetoacetoxy groups in side chains, which are obtained by It is obtained by polymerizing or copolymerizing an acetoacetoxy-containing monomer and other comonomers as needed in the presence of 5 to 50 parts by weight of a chlorinated polyolefin resin having a chlorine content of 15 to 50 wt%. , and (2) isocyanate compounds (for example, see cited patent 2). However, these resin compositions for coating purposes are two-liquid type paints, and there is a problem of shelf life.

Furthermore, there is known a primer for plastics, which is a primer for plastics, which has excellent adhesion on polyolefin substrate moldings, And it has excellent recoating adhesion on the paint film: it contains (A) chlorinated polyolefin with a chlorine content of 16 to 22 wt%, and a weight average molecular weight of 30,000 to 120,000, (B) blocked polyisocyanate, wherein , isocyanurate-type aliphatic and/or cycloaliphatic polyisocyanate blocked with dialkyl malonate and acetoacetate, and (C) polyol resin (see Cited Patent 3, for example). However, although its adhesion to polyolefin-based moldings and sanded paint films is good, there is still a problem of insufficient recoating adhesion when sanding is not performed.

[citing patent 1]

Japanese Unexamined Published Patent Application 2005-139336

[citing patent 2]

Japanese Unexamined Published Patent Application H8-311397

[citing patent 3]

Japanese Unexamined Published Patent Application 2002-121462

Description of the invention

The technical problem to be solved in the present invention

The object of the present invention is to provide primers which have excellent adhesion on plastic substrates, especially polyolefin substrates, and which, when recoated (repainted), are compatible with the underlying paint film, especially Polyurethane resin-based topcoat films have excellent intercoat adhesion; and a coating method using these primers is provided.

A solution to these technical problems

In order to solve the above-mentioned problem, carried out in-depth research, as a result, the inventors found that it can be solved in the following way: In the composition, adding low molecular weight dihydric alcohol and hardening catalyst can greatly improve the recoating adhesion on plastic substrates, such as polyolefin substrate moldings, or on paint films. The present invention is exactly based on this discovery.

That is, the present invention provides a primer characterized in that it contains (A) a chlorinated polyolefin resin with a chlorine content of 5 to 50% by mass and a weight average molecular weight of 1,000 to 100,000, (B) a blocked A polyisocyanate compound, (C) a polyol resin with a hydroxyl value of 30 to 120 mgKOH/g and a weight average molecular weight of 5,000 to 50,000, (D) a diol with a weight average molecular weight of 120 to 1,000, and (E) a hardening catalyst; The total mass of the resin solids of (A), (B) and (C) components contained, the ratio is: 50-90 mass % of (A) component, 45-5 mass % of (B) component , 45-5 mass % of (C) component, 0.5-12 mass % of (D) component and 0.01-1.5 mass % of (E) component.

In addition, the present invention provides a method of coating a plastic molding, characterized in that the above-mentioned primer and top paint are sequentially coated on the plastic molding, and baked and hardened to form a top paint film.

In addition, the present invention provides a method of coating plastic moldings, characterized in that the above-mentioned primer and topcoat are sequentially coated on the plastic moldings, baked and hardened, and then the topcoat film The above primer and topcoat are applied sequentially, baked and hardened.

In addition, the present invention provides a method of coating a molded article, characterized in that the above-mentioned primer is sequentially coated on a topcoat film of a molded article that has been coated with a topcoat and hardened to form a topcoat film. Paint and finish, then bake and harden.

Furthermore, the present invention provides a method of coating a molded article, wherein, in the above method of coating a molded article, the top coat is a one-coat type, two-component type Polyurethane resin paint.

Furthermore, the present invention provides a method of coating a molded article, wherein, in the above method of coating a molded article, the topcoat film has two layers, namely a primer film and a clearcoat film, and At least said clear paint is a two-component polyurethane resin paint.

Furthermore, the present invention provides a method for coating moldings as claimed, wherein, in the above method for coating moldings, the topcoat film has three layers, namely a pigmented primer film , a pearlescent primer film and a clear paint film, and at least the clear paint is a two-component polyurethane resin paint.

Invention effect

By using the primer according to the invention, it is possible to obtain paint films having the properties that their adhesion to primer films on plastic substrates, especially polyolefin substrates, is excellent, and when repainted When overcoated (repainted), the primer film has excellent intercoat adhesion with the urethane resin-based topcoat film constituting the base.

Specific embodiments of the invention

The (A) component chlorinated polyolefin resin used in the present invention has a chlorine content of 5 to 50% by mass, preferably 15 to 35% by mass, most desirably 18 to 25% by mass. In those cases where the chlorine content exceeds 50% by mass, its adhesion to plastic substrates, especially polyolefin substrates, or paint films is poor; in those cases where the chlorine content is less than 5% by mass, in solvents Solubility decreases and storage stability problems arise.

In addition, the (A) component chlorinated polyolefin resin has a weight average molecular weight of 1,000 to 100,000, preferably 5,000 to 90,000, most desirably 10,000 to 80,000. If the weight-average molecular weight exceeds 100,000, there is a problem of poor coating workability; in those cases where it is less than 1,000, the resin itself lacks cohesive strength, and thus there is a problem that a normal paint film cannot be obtained.

A resin obtained by modifying a polymer resin having a polyolefin resin main chain with chlorine is exemplified as the (A) component chlorinated polyolefin resin. Furthermore, polyethylene resins, polypropylene resins, etc., modified polyolefin resins modified with maleic anhydride, etc., polymers having, for example, hydroxyl groups, carboxyl groups, methacryloyl groups, acryloyl groups or epoxy groups at molecular terminals or in molecular chains, etc. Olefin-based polymer compounds are also exemplified as the polyolefin resin.

Examples of the (A) component chlorinated polyolefin resins include chlorinated polyethylene resins, chlorinated polypropylene resins, chlorinated ethylene/propylene copolymers, chlorinated ethylene/vinyl acetate copolymers, among these chlorinated polyolefin resins Olefin resins are modified resins that are copolymerized with acid anhydrides such as maleic anhydride.

In addition, commercial products can be used for the (A) component chlorinated polyolefin resin. Examples of such commercial products include: Superclon 773H, Superclon 822, Superclon 892L, Superclon 832L, Superclon E (produced by Nippon Seishi Chemical Co.), Hardren 14LLB, Hardren CY9122, Hardren HM-21 and Hardren 13-MLJ (produced by Toyo Kasei produced by Kogyo Co.).

The (B) component blocked polyisocyanate compound used in the present invention is a compound in which isocyanate groups of a polyisocyanate compound having two or more isocyanate groups in one molecule are blocked with a blocking agent. When the blocking agent is removed, the blocked polyisocyanate compound can be expected to react with the (C) component polyol resin. In addition, it can ensure the compatibility of the (A) component chlorinated polyolefin resin with the (C) component polyol resin, and can function to improve the affinity with the top paint film.

There is no particular limitation on the polyisocyanate compound as long as it is a kind commonly used in the coating application field, and various polyisocyanates may be used. Various polyisocyanates, such as aromatic polyisocyanates and aliphatic or cycloaliphatic polyisocyanates, can be used as such polyisocyanates. Toluene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), xylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), 2- Isocyanatoethyl-2,6-diisocyanatohexanoate (LTI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), hydrogenated xylene Diisocyanate (HXDI) and the like are preferable examples of such polyisocyanate. Furthermore, the polyisocyanic acid can be used in the form of, for example, a biuret-type, adduct-type or isocyanurate-type prepolymer. From the viewpoint of weather resistance, it is preferable to use aliphatic polyisocyanate. One polyisocyanate may be used alone, or a combination of polyisocyanates may be used.

The blocking agent used as the blocking agent of the polyisocyanate compound can be appropriately selected according to the removal temperature, and examples thereof include oxime, active methylene compound, dialkyl malonate, acetoacetate, ε-caprolactam , β-diketone, etc. A blocked polyisocyanate compound may be used alone, or a combination of these compounds may be used.

The (C) component diol used in the present invention improves the adhesion of the primer film to the top paint film, and in the case where a hardener is used in the top paint, especially in the In the case where the top coat is a polyurethane resin-based paint, it acts to increase cohesive strength by reacting with polyisocyanate migrated from the polyurethane-based paint.

The (C) component polyol resin has a hydroxyl value of 30-120 mgKOH/g, preferably 40-70 mgKOH/g, and a weight average molecular weight of 5,000-50,000, preferably 7,000-20,000. If the hydroxyl value of the polyol resin is less than 30 mgKOH/g, the adhesion will be reduced due to insufficient crosslinking density of the obtained paint film; ) resulting in reduced storage stability of the primer, which is therefore not desirable. In addition, if the weight-average molecular weight of the (C) component polyol resin is less than 5,000, a sufficiently crosslinked paint film cannot be obtained and the adhesion is insufficient; if it exceeds 50,000, compatibility with chlorinated polyolefin resins may will decrease, and as a result, the workability at the time of coating will be deteriorated. In addition, the (C) component polyol resin has an acid value of preferably 0 to 25 mgKOH/g, most desirably 0 to 10 mgKOH/g. If the acid value of the (C) component polyol resin exceeds 25 mgKOH/g, its compatibility with chlorinated polyolefins will decrease, resulting in a decrease in the storage stability of the paint, so this is not desirable .

As the (C) component polyol resin, various polyol resins having the above-mentioned properties can be used, and these polyol resins include acrylic polyol resins and polyester polyol resins. The acrylic polyol resin can be obtained by polymerizing or copolymerizing a hydroxyl group-containing polymerizable unsaturated monomer with (meth)acrylate and/or other comonomers as needed.

Examples of the hydroxyl group-containing polymerizable unsaturated monomer include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, 1,4-butyl Diol mono(meth)acrylate, etc. In addition, the alkyl alcohol residue having 1 to 18 carbon atoms forming the (meth)acrylate may be any alcohol residue having a linear, branched or cyclic alkyl group. One of these may be used, or a combination of two or more may be used.

Examples of copolymerizable (meth)acrylates include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, (meth)acrylate base) isopropyl acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, Cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, etc.; cyclic hydrocarbon esters of (meth)acrylate, such as adamantyl methacrylate Esters, isobornyl (meth)acrylate, etc.; aromatic hydrocarbon esters of (meth)acrylate, such as phenyl (meth)acrylate, etc. One of these may be used, or a combination of two or more may be used.

Other copolymerizable unsaturated monomers include: Hosmer (trade name, produced by Unichemical Co.), epoxy-containing (meth)acrylates such as glycidyl (meth)acrylate, methacrylic acid 3,4 - Epoxycyclohexyl methyl ester, allyl methacrylate, 3,4-epoxycyclohexyl methyl acrylate, etc.; aromatic compounds containing polymerizable double bonds, such as styrene, α-methyl Styrene, p-vinyl toluene, etc.; acrylamide compounds such as methacrylamide, acrylamide, N,N-dimethylmethacrylamide, N,N-dimethylacrylamide, etc., 2,2,6, 6-tetramethyl-4-piperidinyl acrylate; and aliphatic vinyl ether compounds such as ethyl vinyl ether, isopropyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, Isobutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, etc.

In addition, they include: 2,3-dihydrofuran; trimethoxysilylpropyl (meth)acrylate; maleic anhydride esters, itaconic anhydride esters, maleate esters, fumarate esters; acrylic acid esters Nitrile; allyl-containing compounds, such as allyl glycidyl ether; alkyl esters of crotonic acid, such as methyl crotonate, ethyl crotonate, propyl crotonate, etc.; aliphatic carboxylic acid vinyl esters, Such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl crotonate, vinyl caprylate, vinyl caproate, vinyl laurate, vinyl stearate, etc.; alicyclic Vinyl carboxylate, such as vinyl cyclohexanecarboxylate, etc.; and vinyl carboxylate, such as vinyl benzoate, vinyl cinnamate, vinyl p-tert-butylbenzoate, etc.

In addition, the other comonomers include methacrylic acid, acrylic acid, itaconic acid, methylfumaric acid, maleic acid, fumaric acid, ω-carboxy-polycaprolactone (n=2) mono Acrylate (for example, Aronix M-5300 (trade name, manufactured by Toa Gosei Kagaku Kogyo Co.)), monohydroxyethyl phthalate (for example, Aronix M-5400 (trade name, manufactured by Toa Gosei Kagaku Kogyo Co.) . produced)) and acrylic acid dimers (for example, Aronix M-5600 (trade name, produced by Toa Gosei Kagaku Kogyo Co.)). One of these may be used, or a combination of two or more may be used.

The copolymerizable (meth)acrylic acid ester and other copolymerizable unsaturated monomers are not essential components. When designing the paint film according to the base material and target application, they can be appropriately selected and adopted as required. .

The polymerization or copolymerization method of the hydroxyl-containing polymerizable unsaturated monomer is not particularly limited. For example, known methods such as solution polymerization, suspension polymerization, emulsion polymerization, bulk polymerization, precipitation polymerization, etc. in organic solvents can be used. . In addition, there is no particular limitation on the polymerization system, for example, radical polymerization, cationic polymerization or anionic polymerization can be used.

Among these methods, radical polymerization is preferable from an industrial point of view. Organic peroxides such as tert-butyl hydroperoxide, cumene hydroperoxide, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, tert-hexyl peroxy-2-ethylhexanoate, Methyl ethyl ketone peroxide, etc., or azo-based initiators such as 2,2'-bis-azo(2,4-dimethyl-valeronitrile), 2,2'-azobis(2-methylpropionitrile) (AIBN), 2,2'-azobis(2-methyl)butyronitrile), etc., can be given as preferable examples of the polymerization initiator usable for the radical polymerization. Of course, the initiator is not limited to these examples. One of these radical initiators may be used, or a combination of two or more may be used.

During free radical polymerization, a reaction temperature of 60 to 150°C is generally preferred. If the temperature is lower than 60°C, the radical polymerization initiator cannot be broken and the reaction cannot proceed; if it exceeds 150°C, even if the radical polymerization initiator breaks and generates free radicals, their lifespan is very short, and the chain growth reaction cannot be done effectively. The polymerization time is controlled by the reaction temperature and other conditions, and usually cannot be fixed, but a time of 2 to 6 hours is usually satisfactory.

In addition, the (C) component polyester polyol resin can be obtained by reacting a polybasic acid with a polyhydric alcohol. Examples of the polybasic acid include phthalic anhydride, tetrahydrophthalic anhydride, isophthalic acid, maleic anhydride, fumaric acid, trimellitic anhydride, methylenetricyclohexenetricarboxylic anhydride, pyromellitic anhydride , itaconic acid, adipic acid, sebacic acid, azelaic acid, hexahydrophthalic anhydride, humic anhydride, succinic anhydride, hettoic anhydride, etc. One kind of polybasic acid may be used, or two or more kinds may be used. Examples of polyols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, butylene glycol, hexylene glycol, trimethylolethane, trimethylolpropane, pentaerythritol, di Pentaerythritol, sorbitol, etc., and lactones such as caprolactone, adducts of these alcohols. One kind of polyol may be used, or two or more kinds may be used.

In addition, monobasic acid, fatty acid, oil components, etc. can also be used to modify the polyester polyol resin. In addition, hydroxyl groups can be easily introduced into the polyester polyol resin by means of a polyol having three or more hydroxyl groups in one molecule.

One kind of (C) component polyol resin may be used, or a combination of two or more kinds may be used.

In the invention of this application, the ratios of (A) component, (B) component and (C) component contained are such that relative to (A) component, (B) component and (C) component There are 50 to 90% by mass of the (A) component, 45 to 5% by mass of the (B) component, and 45 to 5% by mass of the (C) component. Preferably, 60-80 mass % of (A) component, 30-10 mass % of (B) component, 30-10 mass % of (C) component are present.

Here, the above ratios of (A) component, (B) component and (C) component contained refer to the contained (A) component, (B) component and (C) component respectively. The proportion of resin solids. In addition, the resin solid content refers to the residue after heating measured by the method described in JIS K5601-1-2.

In those cases where the (A) component is less than 50% by mass, the adhesion of the primer film to the plastic substrate decreases; The adhesion of the film is reduced. In those cases where the (B) component is less than 5% by mass, the adhesion of the primer film to the topcoat film decreases; in those cases where the (B) component exceeds 50% by mass, the Decreased adhesion. In those cases where the (C) component is less than 5% by mass, the adhesion of the primer film to the topcoat film decreases; in those cases where the (C) component exceeds 45% by mass, the Decreased adhesion.

The (D) component diol used in the present invention plays a role in improving the wettability of the chlorinated polyolefin resin to plastic materials, and when recoating, it plays a role in improving the resistance to the topcoat film constituting the substrate. , especially the role of the wetting ability of the polyurethane resin-based topcoat film, and improved adhesion. In the urethane resin-based topcoat film constituting the lower layer in contact with the primer, with the unreacted isocyanate compound remaining in the vicinity of the interface with the primer, the diisocyanate compound having a molecular weight lower than that of the (C) component polyol Alcohols, based on their high mobility, easily migrate from the primer film to the vicinity of the interface, and there is a high possibility of reacting with the unreacted isocyanate compound, which is considered to have great Visible effect, when recoating, it can improve the intercoat adhesion of the primer film and the topcoat film.

(D) The weight average molecular weight of the component diol is 120-1,000, preferably 120-800. In those cases where the weight-average molecular weight of the (D) component is less than 120, the storage stability of the primer decreases due to decreased solubility in main aryl solvents, which is not desirable. In those cases where the weight-average molecular weight exceeds 1,000, no improvement in adhesion on the topcoat film constituting the underlayer, particularly on the polyurethane resin-based topcoat film, is observed.

(D) Component Examples of low molecular weight diols include dipropylene glycol, triethylene glycol, hydrogenated bisphenol A, and the like. In addition, diols which are reaction products of dibasic acids and excess diols, and lactones such as caprolactone, adducts of these diols, etc., can also be used as (D) component low molecular weight diols. Alcohols. Examples of the dihydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, neopentyl glycol, pentanediol, hexanediol, heptanediol, octanediol, alcohol, butyl ethyl propylene glycol, cyclohexanediol, cyclohexanedimethanol, and phenyldimethanol. Examples of the dibasic acid include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, hexadioic acid, Hydrogen terephthalic acid, maleic acid, fumaric acid, etc., and anhydrides of these dibasic acids. In addition, they can also be used monoglycidyl compounds such as butyl glycidyl ether containing monoglycidyl group, 2-ethylhexyl glycidyl ether, sec-butylphenyl glycidyl ether, glycidyl neodecanoate Esters, etc. are modified.

In the present invention, component (D) is contained in a proportion of 0.5 to 12% by mass, preferably 1 to 10% by mass, most desirably 1.5 to 8% by mass, relative to (A) component, (B ) component and (C) the total mass of resin solid content of component. If the proportion of the contained (D) component is less than 0.5% by mass, the adhesion of the primer film to the top paint film constituting the base, especially on the polyurethane resin-based top paint film is insufficient; In those cases of 12% by mass, since the compatibility with the main chlorinated polyolefin resin constituting the (A) component decreases, the storage stability of the primer decreases, which is not desirable.

In addition, the ratio of the (D) component to be contained means the ratio of the active ingredient of the (D) component to be contained. Here, in the case of dilution with a solvent or the like, the effective ingredient means not Components including solvents and the like.

The (E) component hardening catalyst used in the present invention should be a catalyst capable of promoting the reaction between the (D) component diol and the reactive components contained in the top paint film constituting the substrate, and used for Catalysts in polyurethane resins are particularly desirable. In the case where the top paint film constituting the base is a polyurethane resin-based paint film, the reaction between hydroxyl groups in the primer layer of the recoat paint and unreacted isocyanate groups in the polyurethane resin-based top paint film constituting the base can be promoted. Adhesion is also improved when recoating without sanding.

Actually, the (E) component hardening catalyst is, for example, a tin compound or a zinc compound. Examples of tin compounds include tin halides, such as tin chloride, tin bromide, etc., and organotin compounds, such as dibutyltin diacetate, dibutyltin dilaurate, etc.; examples of zinc compounds include zinc halides, such as zinc chloride, bromine Zinc chloride, etc., zinc salts of organic acids such as zinc octoate, zinc laurate, etc. As the hardening reaction catalyst, one kind of tin compound or zinc compound, or a combination of two or more kinds may be used, and other hardening reaction catalysts may also be used at the same time.

In the present invention, the (E) component is contained in a proportion of 0.01 to 1.5% by mass, preferably 0.02 to 1.0% by mass, most desirably 0.05 to 0.8% by mass, relative to (A) component, (B ) component and (C) the total mass of resin solid content of component. If the proportion of the (E) component is less than 0.01% by mass, the effect of accelerating the hardening reaction cannot be satisfactorily achieved; in those cases where it exceeds 1.5% by mass, the recoating adhesion decreases, which is considered to be This is undesirable due to excessive hardening of the paint film.

In addition, the ratio of the (E) component to be contained means the ratio of the effective components of the (E) component to be contained, and in the case of diluting it with a solvent or the like, the effective component means excluding components of solvents, etc.

Colored pigments, true pigments, organic solvents, and various additives can be used in the primer of the present invention as required. Examples of colored pigments include organic pigments such as azo lake-based pigments, phthalocyanine pigments, indigo-based pigments, perylene-based pigments, perylene-based pigments, quinophthalone-based pigments, dioxazine-based pigments, quinacridone-based pigments etc.; inorganic pigments such as chrome yellow, iron oxide yellow, iron oxide red, titanium dioxide, etc. True pigments include kaolin, talc, and the like.

In addition, there is no particular limitation on the organic solvent as long as the various components can be dissolved therein, but those that do not react with the isocyanate compound are preferred. Examples thereof include aliphatic hydrocarbons such as n-hexane, n-heptane, n-octane, etc.; aromatic hydrocarbons such as benzene, toluene, xylene, etc.; halogenated hydrocarbons such as chloroform, carbon tetrachloride, etc.; alcohols such as methanol, ethanol, n-propyl Alcohol, isopropanol, n-butanol, etc.; ethers such as dibutyl ether, tetrahydrofuran, 1,4-dioxane, etc.; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.; and esters such as ethyl acetate , n-propyl acetate, n-butyl acetate, etc. One of these solvents may be used, or a combination of two or more may be used. There is no particular limitation on the compounding method of various components, or the adding method of luminescent pigment, coloring pigment, organic solvent and various additives and resins, and various methods can be adopted, and the order of mixing and adding can also be changed.

After adjusting the primer to a desired viscosity by heating and adding an organic solvent as needed, the primer is then coated with a commonly used coating machine such as an air sprayer, airless sprayer, electrostatic air sprayer, flow coater or dip coater. Application by type coating machine, or by brush, can be used as a suitable application method with the primer of the present invention, but air spray application is preferred. The dry film thickness of the primer film is preferably 2 to 15 μm, most desirably 4 to 10 μm.

After application of the primer of the invention, the topcoat is applied wet-on-wet, preferably without baking the primer. The top paint may be one-coat type, two-coat type, or three-coat type paint, but for constituting the uppermost paint film layer, two-component polyurethane resin paint is preferred. The urethane resin-based top paint is not particularly limited, but it should allow the paint film to be formed by the reaction between polyol and isocyanate compound.

A spreadable finish can be a solid paint, or a paint with a metallic tint. The dry film thickness of the topcoat is preferably 15-40 μm, most desirably 20-35 μm. Secondary coating type paint is usually the combination of colored primer or pearlescent primer such as metal primer and clear paint, and the dry film thickness of the primer is preferably 10 to 20 μm. The dry film thickness of the clear lacquer is preferably 20-40 μm, most desirably 25-35 μm. The three-way coating type paint is usually a colored primer primer, a combination of a pearlescent primer primer and a clear paint. The dry film thickness of the colored primer primer is preferably 5 to 15 μm, and the pearlescent primer primer The dry film thickness of the lacquer is preferably 5-15 μm and the dry film thickness of the clear lacquer is preferably 20-40 μm, most desirably 25-35 μm. Where these paints are applied in layers, they are all applied wet-on-wet, preferably in the uncured state.

The baking and drying conditions of the polyurethane resin-based topcoat are preferably at 20-150° C. for 5 minutes to 3 days; at 80-140° C. for 10-30 minutes, which is the most desirable.

Moldings coated with the primer according to the invention may be, for example, moldings containing polyolefin substrates, such as polyethylene, polypropylene, etc., and plastic substrates containing polyolefins or the like. In addition, the primer can also be used on moldings containing plastic substrates such as ABS resin, PC resin, nylon, and the like.

In the present invention, recoating (repainting) includes, for example, a method in which the primer and top paint of the present invention are sequentially applied to a mold that has been coated with a top paint and hardened to form a top paint film. on plastics, baked and hardened; and a method in which the recoating is carried out after the primer and topcoat of the present invention are sequentially applied and baked hardened in the event of dust deposits, or damage to the paint film of. In this case, after removing the dust, without sanding the entire topcoat film, the primer is applied again, and the primer and topcoat should be applied in substantially the same manner as in the first case. way, sequential coating and baking. In addition, recoating (repainting) can be performed even in the case where a part of the topcoat film constituting the base has been peeled off, and by sequentially applying the primer and topcoat and baking, it is possible to obtain Paint film with excellent adhesion.

Examples of coated articles obtainable by the coating method of the present invention include structural materials, metal products, plastic products, rubber products, and the like. In practice, these include cars and car parts (e.g. bodywork, bumpers, spoilers, mirrors, wheels, interior trim, etc. made of various materials), metal sheets such as steel sheets, bicycles, bicycle parts, Materials used on roads (e.g., guardrails, traffic signs, sound-absorbing walls, etc.), materials used in tunnels (e.g., clapboards, etc.), ships, railway vehicles, aircraft, musical instruments, household appliances, construction materials, containers , office supplies, sporting goods, toys, etc.

exemplary embodiment

Hereinafter, the present invention will be described more practically by means of Preparation Examples, Exemplary Examples and Comparative Examples. Also, the present invention is not limited by these exemplary embodiments. The terms "part" and "%" hereinafter mean "parts by mass" and "% by mass", respectively, although not specifically noted. In addition, in Tables 1-6, the unit of the numerical value which shows the quantity of each compounded component is mass parts.

In addition, in Examples and Comparative Examples, the evaluation of each characteristic was performed by the method described below.

<Evaluation method of paint and paint film>

(primer storage stability)

The primer was stored at 40°C for 10 days, and its state was evaluated based on the following criteria.

○: No abnormality observed

△: Slight separation observed

×: Clear separation was observed

(Primer coating workability)

The surface of a black commercial polypropylene plate (length 70 mm x width 150 mm x thickness 3 mm) was wiped with isopropanol to remove dust and contamination deposited on the sample for coating. The viscosity of the primer shown in Table 4 or 5 was then adjusted to No. 4 Ford cup (20° C.) with xylene for 11 seconds, coated with an air sprayer, and the coating workability was evaluated according to the criteria shown below.

○: No abnormality, coating possible

×: Due to the condensation of the paint, the coating cannot be performed, or a spider web state occurs during the coating process, and the normal coating cannot be performed

(adhesion of the first top coat)

The topcoat adjusted to the viscosity of No. 4 Ford Cup (25°C) for 12 seconds with a diluting solvent (butyl acetate/xylene=70/30 (mass ratio) solvent mixture) is sprayed by air in a wet-on-wet manner On the primer film, let it stand at room temperature for 5 minutes, then keep it at 90°C for 20 minutes and dry, and the primer film is substantially in accordance with the method described above to form a dry film of 6-8 μm Thickness way, coated onto black commercial polyolefin panels. In all cases, including two-coat and three-coat types, the application is applied wet-on-wet such that in the case of one-coat types the dry film thickness of the topcoat is 25 μm, in the case of a two-coat type primer, the dry film thickness is 15 μm, in the case of a three-coat type pigmented primer, the dry film thickness is 10 μm, and in the three-coat type In the case of a pearlescent base coat, the dry film thickness is 8 μm, and in the case of a clear paint, the dry film thickness is 30 μm. For the test, the obtained coated panel was allowed to stand at room temperature for 60 minutes, and then cut 11 times with a cutter in the length and width directions of the paint film at intervals of 2 mm to obtain 100 squares, which were peeled off with cellophane tape , and the peeling state was evaluated based on the following criteria.

○: The paint film does not peel off (remaining squares expressed as 100/100)

△: Partial paint film peeling off (remaining squares expressed as 90/100～99/100)

×: Paint film peeling (expressed as the remaining squares from 0/100 to 89/100)

In those cases where paint film peeling was observed, the location of peeling was confirmed to be between the substrate and the primer film or between the primer film and the top paint film.

(Adhesion of recoated topcoat to first topcoat)

The topcoat adjusted to the viscosity of No. 4 Ford Cup (25°C) for 12 seconds with a diluting solvent (butyl acetate/xylene=70/30 (mass ratio) solvent mixture) is sprayed by air in a wet-on-wet manner On the primer film, let it stand at room temperature for 5 minutes, then keep it at 100°C for 40 minutes and dry, and the primer film is substantially in accordance with the method described above to form a dry film of 6-8 μm Thickness way, coated onto black commercial polyolefin panels. In all cases, including two-coat and three-coat types, the application is applied wet-on-wet such that in the case of one-coat types the dry film thickness of the topcoat is 25 μm, in the case of a two-coat type primer, the dry film thickness is 15 μm, in the case of a three-coat type pigmented primer, the dry film thickness is 10 μm, and in the three-coat type In the case of a pearlescent base coat, the dry film thickness is 8 μm, and in the case of a clear paint, the dry film thickness is 30 μm. The coated panels are left to stand at room temperature for 24 hours, and then, in substantially the same manner as in the first case, the primer and topcoat are applied wet-on-wet by air spray and left at room temperature for 5 minutes, and dried at 80° C. for 20 minutes.

For the test, the obtained coated panel was allowed to stand at room temperature for 60 minutes, and then cut 11 times with a cutter in the length and width directions of the paint film at intervals of 2 mm to obtain 100 squares, which were peeled off with cellophane tape , and the peeling state was evaluated based on the following criteria.

○: The paint film does not peel off (remaining squares expressed as 100/100)

△: Partial paint film peeling off (remaining squares expressed as 90/100～99/100)

×: Paint film peeling (expressed as the remaining squares from 0/100 to 89/100)

Resin preparation example 1 (preparation of glycol resin solution)

Add 1,6-hexanediol (561 parts) and 347.1 parts of adipic acid into a glass flask with a volume of 2 L equipped with a thermometer and a stirrer. After slowly raising the temperature to 140 ° C, within 3 hours, the temperature raised to 190°C. The mixture was kept at 190°C for 2 hours for esterification, and then the temperature was raised to 210°C within 2 hours for esterification until the acid value of the resin dropped below 1. The resin thus obtained was cooled, and 91.9 parts of xylene was added to obtain a diol solution D-1 having a weight average molecular weight of 330 and a resin solid content (effective component) of 90% by mass.

Resin Preparation Examples 2-4 (Preparation of Glycol Resin Solution)

In the same manner as in Preparation Example 1, the raw materials shown in Table 1 were used for resin synthesis to obtain diol resin solutions D-2 to D-4 shown in Table 1. The raw material Cardura E-10 in Table 1 is tertiary carboxylic acid monoglycidyl ester (manufactured by Japan Epoxy Resin Co.).

Table 1

Resin preparation example 5 (preparation of polyester polyol resin solution)

Add butyl ethyl propylene glycol (187.3 parts), 18.8 parts of trimethylolpropane, 94 parts of 1,6-hexanediol, 31.3 parts of phthalic anhydride and 295.2 parts of adipic acid into a thermometer equipped with a thermometer and a stirrer. 1. In a glass flask with a volume of 2 L, after slowly raising the temperature to 140° C., the temperature was raised to 190° C. within 3 hours. The mixture was kept at 190° C. for 2 hours, then, after the esterification reaction started, the temperature was raised to 210° C. within 2 hours to carry out the esterification reaction until the acid value of the resin dropped below 10. The thus obtained resin was cooled, and 373.4 parts of xylene was added to obtain polyester polyol resin solution C-1 having a weight average molecular weight of 14,000, a hydroxyl value of 45, an acid value of 8, and a solid content of 60% by mass.

Resin preparation example 6 (preparation of polyester polyol resin solution)

In the same manner as Preparation Example 5, the raw materials shown in Table 2 were used for resin synthesis to obtain polyester polyol resin solution C-2 shown in Table 2.

Table 2

Resin preparation example 7 (preparation of acrylic polyol resin solution)

Xylene (300 parts) was added into a glass flask with a volume of 2 L equipped with a thermometer, a stirrer, a reflux condenser and a monomer dropping device, and the temperature was raised slowly to achieve reflux. While maintaining the reflux state, within 3 hours, drop 180 parts of styrene, 30 parts of methyl methacrylate, 197 parts of stearyl methacrylate, 191.4 parts of Praxel FM-2 (trade name , produced by Daiseru Kagaku Kogyo Co.; hydroxyethyl methacrylate added with 2 mol ε-caprolactone), 1.8 parts of acrylic acid and 17 parts of polymerization initiator Perbutyl z (trade name, produced by Nippon Yushi Co.; benzene peroxide tert-butyl formate) mixed solution. After the dropwise addition was completed, the reflux state was maintained for another 3 hours, and then 1 part of the polymerization initiator Perbutylz and 10 parts of xylene were mixed and added dropwise from a dropping device. Then, after maintaining at the reflux temperature for another 2 hours, the reaction was continued, 71.8 parts of xylene was added, and the mixture was cooled to room temperature to obtain an acrylic polyol resin solution C-3 with a resin solid content of 61% by mass.

Resin preparation examples 8-12 (preparation of acrylic polyol resin solution)

In the same manner as Preparation Example 7, resin synthesis was performed using the raw materials shown in Table 3, and acrylic polyol resin solutions C-4 to C-8 shown in Table 3 were obtained.

Primer preparation example 1

A chlorinated polypropylene resin solution (trade name Hardren CY9122, produced by Toyo KaseiKogyo Co., a maleic anhydride-modified chlorinated polypropylene resin with a chlorine content of 22% by mass and a weight-average molecular weight of 50,000 to 60,000, resin solid Divided into 20%) (487.5 parts), 99 parts of Typake CR-90 (titanium dioxide, produced by Ishihara Sangyo Co.), 0.1 part of pigment black FW200 pellets (carbon black, produced by Degussa Co.) and 0.9 parts of TSY-1 (yellow pigment, produced by Toda Pigment Co.), was added to a dispersion vessel and dispersed until the particle size was less than 15 μm. Dispersion was stopped after reaching the target particle size, and 40 parts of blocked isocyanate (trade name Desmodur BL3175, produced by Sumitomo Bayer Co., HDI isocyanate blocked with MEK oxime, NCO content of 11.2%, and residual amount of 75% after heating were added. ), 36.9 parts of resin preparation example 7 prepared acrylic polyol C-3, 5 parts of resin preparation example 1 prepared dibasic alcohol D-1, 0.9 part of dibutyltin dilaurate and 329.7 parts of xylene, fully stirred, Primer P-1 of Primer Preparation Example 1 shown in Table 4 was obtained.

Primer preparation examples 2-21

In the same manner as Primer Preparation Example 1, primers P-2 to P-21 shown in Tables 4 and 5 were obtained.

The meanings of the abbreviations and product names in the table are as follows:

1) Typake CR-90: Titanium dioxide, produced by Ishihara Sangyo Co.

2) Acicular conductive titanium dioxide: conductive titanium dioxide, produced by Ishihara Sangyo Co.

3) Pigment black FW200 pellets: carbon black, manufactured by Degussa Co.

4) PRINTEX L: Conductive carbon black, produced by Degussa Co.

5) TSY-1: yellow pigment, produced by Toda Pigment Co.

6) Hardren CY9122: Produced by Toyo Kasei Kogyo Co., a maleic anhydride-modified chlorinated polypropylene resin with a chlorine content of 22% by mass, a weight-average molecular weight of 50,000-60,000, and a residue after heating of 20%.

7) Superclon 892L: Produced by Nippon Seishi Chemical Co., a maleic anhydride-modified chlorinated polypropylene resin with a chlorine content of 22% by mass, a weight-average molecular weight of 60,000 to 70,000, and a residue after heating of 20%.

8) Desmodur BL3175: Produced by Sumitomo Bayer Urethane Co., HDI isocyanurate blocked with MEK oxime, NCO content 11.2% by mass, residue after heating 75% by mass.

9) Desmodur BL3272MPA: Produced by Sumitomo Bayer Urethane Co., HDI isocyanurate blocked with ε-caprolactam, NCO content 10.2% by mass, residue after heating 72% by mass.

10) Desmodur BL4265SN: Produced by Sumitomo Bayer Urethane Co., IPDI isocyanurate blocked with MEK oxime, NCO content 8.9% by mass, residue after heating 65% by mass.

Topcoat preparation example 1 (two-component polyurethane resin paint for one coat purpose)

Acrylic resin LB-9020 (manufactured by BASF Coatings Japan Co., residual amount after heating is 55% by mass, hydroxyl value 56 mgKOH/g) (45.5 parts), 24 parts of TypakeCR-90 (titanium dioxide, manufactured by Ishihara Sangyo Co. production), 0.1 part of pigment black FW200 pellets (carbon black, produced by Degussa Co.) and 0.6 parts of TSY-1 (yellow pigment, produced by TodaPigment Co.), were added into a dispersion vessel for dispersion until the particle size was less than 10 μm. After reaching the target particle size, the dispersion was stopped, the matter was taken out, and 0.2 parts of surface conditioner Modaflow (produced by Monsanto Co., acrylic acid copolymer, residual amount after heating was 100% by mass), 10 parts of xylene and 13.2 parts of butyl acetate, fully stirred in Disper until uniform to prepare the main component of the two-component topcoat T-1 for the purpose of one coat. Using Sumidure N75 (manufactured by Sumitomo Bayer Co., polyisocyanate resin, residual amount after heating is 75% by mass, NCO content is 16.5% by mass) as a hardening agent, and immediately before starting coating, it was adjusted to 93.6 A ratio of 6.4 parts of the main component to 6.4 parts of the hardener was mixed and stirred until a homogeneous mixture was obtained before use.

Topcoat Preparation Example 2 (Primer Coat for Secondary Coating Purposes)

Acrylic resin LB-9020 (produced by BASF Coatings Japan Co., the residue after heating is 55% by mass, and the hydroxyl value is 56 mgKOH/g) (45.5 parts), 6 parts of rheology modifier LC-0988 (produced by BASF Coatings Japan Co. production, inorganic system, the residue after heating is 10% by mass), 2.5 parts of aluminum flake pigment Alpaste TCR3040 (trade name, produced by ToyoAluminum Co., the residue after heating is 80% by mass, average particle diameter ( D ₅₀ ) of 17 μm, average thickness of 0.8 μm), 3 parts of Alpaste 6340NS (trade name, produced by Toyo Aluminum Co., 71% by mass remaining after heating, average particle diameter (D ₅₀ ) of 13 μm, average thickness of 0.29 μm), 3.3 parts of Desmodur BL3175 (trade name, produced by SumitomoBayer Urethane Co., HDI isocyanurate blocked with MEK oxime, NCO content is 11.2% by mass, residue after heating is 75% by mass), 0.2 Parts of surface conditioner Modaflow (produced by Monsanto Co., acrylic acid copolymer, the residue after heating is 100%), 10 parts of xylene and 29.5 parts of butyl acetate were mixed together and stirred in Disper for 10 minutes to provide a uniform mixture, and prepare a one-pack metal primer T-2 for secondary coating purposes.

Topcoat Preparations 3 and 4 (Primercoats for Surfacer Purposes)

In the same manner as in Topcoat Preparation Example 2, one-component metal primers T-3 and T-4 for the purpose of secondary coating shown in Table 6 were prepared.

Topcoat Preparation Example 5 (Primercoat for Secondary Coating Purposes)

The main components of the two-component metal topcoat T-5 for the purpose of secondary coating were prepared in the following manner: in the same manner as the topcoat preparation example 2, the ingredients shown in Table 4 except SumidureN75 The ingredients are mixed. Sumidure N75 was used as a hardener, and immediately before coating, it was mixed at a ratio of 96.5 parts of the main ingredient to 3.5 parts of hardener, stirred to a homogeneous state, and used.

Topcoat Preparation Example 6 (Pigmented Primer for Three-Coat Purposes)

The main components of the two-component type colored primer primer T-6 for the purpose of three-coating were prepared in the following manner: the pigments shown in Table 6 were dispersed in the same manner as in Topcoat Preparation Example 1, Add remaining ingredients except Sumidure N75 and mix well. Sumidure N75 as a hardener was mixed at a ratio of 96.5 parts of the main component to 3.5 parts of hardener immediately before coating, stirred until homogeneous and used.

Topcoat Preparation Example 7 (Pigmented Primer for Three-Coat Purposes)

In the same manner as in Topcoat Preparation Example 6, disperse the pigments shown in Table 6, add the remaining raw materials, and stir evenly to prepare a single-component colored primer T-7 for three-coating purposes.

Topcoat Preparation Example 8 (Pearlite Primer for Three-coat Purposes)

The main components of the two-component pearlescent primer T-8 for the purpose of three-coating were prepared in the same manner as the topcoat preparation example 5, except that the aluminum pigment was replaced by pearlescent pigment. Sumidure N-75 as a hardener was mixed at a ratio of 96.5 parts of the main component to 3.5 parts of hardener immediately before coating, stirred until homogeneous and used.

Topcoat Preparation Example 9 (Pearlite Primer for Three Coating Purposes)

A one-liquid type pearlescent top coat T-9 for the purpose of three-coating was prepared in the same manner as the topcoat preparation example 2, except that the aluminum pigment was replaced with a pearlescent pigment.

Topcoat preparation example 10 (transparent paint)

The surface conditioner Modaflow (0.2 parts) and 4.8 parts of butyl acetate were mixed with 80 parts of acrylic resin LB-9040 (manufactured by BASF Coatings Japan Co., the residual amount after heating was 55% by mass, and the hydroxyl value was 78 mgKOH/g) Mix, stir in Disper for 10 minutes to prepare a homogeneous main component of two-component clear paint T-10. Sumidure N-75 as a hardener is mixed at a ratio of 85 parts of the main component to 15 parts of hardener immediately before coating, stirred until homogeneous and used.

Abbreviations and trade names shown in the table have the meanings shown below.

11) Iriod in 103WNT: (produced by Merck Co., mica pigment)

12) Alpaste TCR3040: an aluminum pigment produced by Toyo Aluminum Co., the residual amount after heating is 80% by mass, and the average particle diameter (D ₅₀ ) is 17 μm

13) Alpaste 6340NS (an aluminum pigment produced by Toyo Aluminum Co., the residual amount after heating is 71% by mass, and the average particle diameter (D ₅₀ ) is 13 μm

14) Sumidure N-75: Produced by Sumitomo Bayer Urethane Co., polyisocyanate resin, the residue after heating is 75%, and the NCO content is 16.5% by mass

15) Yuban 122: Produced by Mitsui Kagaku Co., butylated melamine resin, the residual amount after heating is 60% by mass

16) Modaflow: Produced by Monsanto Co., an acrylic copolymer, the residual amount after heating is 100% by mass

(Example 1)

Using P-1 as the primer and T-1 as the topcoat, based on the above-mentioned evaluation method of paint and paint film, the storage stability of the primer, the operability of primer coating, and the first topcoat after coating were carried out. Adhesion to the topcoat, adhesion of the recoated topcoat on the first topcoat, and the evaluation results are shown in Table 7.

(Embodiments 2-12)

In substantially the same manner as in Example 1, the test was performed except that the topcoat was replaced with the composition shown in Table 7, and the evaluation results are shown in Table 7.

(comparative examples 1～9)

The test was carried out in substantially the same manner as in Example 1, except that the composition shown in Table 8 was used instead of the topcoat, and the evaluation results are shown in Table 8.

<Conclusion>

Although, as shown in Examples 8 to 12 in Table 7, the adhesion of the recoated paint film is slightly reduced, the level of reduction will not cause problems in practical application, and the primer of the present invention has excellent shelf life. Stability, coating workability, and the ability to obtain a paint film with the primer that does not present adhesion problems between the first paint film and the recoated paint film.

However, in those cases where the (A), (B) and (C) components were outside the scope of the claimed paint, as shown in Comparative Examples 1 to 4, the adhesion of the primer to the substrate decreased (as shown in Comparative Examples 1, 2 and 4), or the adhesion of the topcoat to the primer was slightly reduced, and the adhesion was insufficient when recoated (as shown in Comparative Example 3). Furthermore, in those cases where the blended polyols had property values outside the range of the claimed paint, the adhesion of the primer to the substrate was reduced as shown in Comparative Example 5, or as shown in Comparative Example 6 As shown in and 7, there were problems in the coating workability and storage stability of the primer. Furthermore, when the (D) component and (E) component were outside the range of the present invention, as shown in Comparative Examples 8 and 9, the recoating adhesion was insufficient.

From the above results, it can be seen that the primer of the present invention has excellent primer storage stability, coating workability, and can obtain a coated product having excellent first top coat adhesion and recoat adhesion.

Claims (7)

1. priming paint, it is characterized in that, it contains (A) cl content is that 5～50 quality %, weight-average molecular weight are 1,000～100,000 chlorinated polyolefin resin, (B) polyisocyanate compound of sealing, (C) hydroxyl value is that 30～120mgKOH/g, weight-average molecular weight are 5,000～50,000 polyol resin, (D) weight-average molecular weight is 120～1,000 dibasic alcohol, and (E) hardening catalyst; With respect to contained (A), (B) and (C) ratio of the total mass of the resin solids of component be, (A) component of 50～90 quality %, (B) component of 45～5 quality %, (C) component of 45～5 quality %, 0.5 (D) component of～12 quality %, and (E) component of 0.01～1.5 quality %, described resin solids refers to, adopt the described method of JIS K5601-1-2 to measure the resistates after heating.

2. the method for coating plastic moulded work is characterized in that, to plastic molded articles, baking is sclerosis also with priming paint claimed in claim 1 and finish paint sequential applications, forms top-coat paint film.

3. the method for coating plastic moulded work is characterized in that, to plastic molded articles, baking is sclerosis also with priming paint claimed in claim 1 and finish paint sequential applications, then with priming paint claimed in claim 1 and finish paint sequential applications on top-coat paint film, baking is sclerosis also.

4. apply the method for moulded work, it is characterized in that, priming paint claimed in claim 1 and finish paint sequential applications have been coated with finish paint, and sclerosis and forming on the top-coat paint film of moulded work of top-coat paint film on it, then toast and harden.

5. such as the method for each described coating moulded work in the claim 2～4, wherein, described finish paint is one application type two-pack type polyurethane resin paint.

6. such as the method for each described coating moulded work in the claim 2～4, wherein, top-coat paint film has two-layer, i.e. priming coat film and transparent paint film, and the described at least clear lacquer is a kind of two-pack type polyurethane resin paint.

7. such as the method for each described coating moulded work in the claim 2～4, wherein, top-coat paint film has three layers, i.e. painted priming coat film, and pearly-lustre priming coat film and transparent paint film, and the described at least clear lacquer is a kind of two-pack type polyurethane resin paint.